Cycles to external renderer
Since there are no further answers: no, this doesn't work out of the box. Converter misses many nodes and some Nodes like "Light Path" are not possible to keep, if you want to use bidirectional path tracing. Node editor in Lux shows a warning sign near the nodes which were not correctly converted. To keep track of the conversion, one should run Blender in Terminal, as errors and warnings will be printed there.

Apart from that, many things can go wrong. The textures packed in .blend won't be loaded, multiple render layers are likely to be a problem.